Everyone has, or has had, a Lister D in their collection in the UK. Over 250,000 produced from the 1920's to the 1960's, it must be one of the highest quantity production runs in the world for an industrial/agricultural engine. It was produced for generating, milking, pumping, sheep-shearing, cement mixing and sawing wood, and probably a few more applications besides those mentioned.
The 8/1 engine in its final form of the 1960's. Sold into Iran in some numbers until the death of the Shah, the 8/1 disposed of the compression change- over valve but retained the mechanical simplicity of its predecessors. The solid flywheels became standard and not just for genset engines. Improvements in fuels and injection pressures enabled the compression change-over valve to be deleted. The square plug on the head is in the position of the valve.
The JK series were the later version of the JP, and provided better power and fuel economy while doing away with the compression change-over valves, which on a six-cylinder industrial engine took some time to operate when starting from cold. The JS engine which followed was mechanically almost identical. This picture shows an industrial engine with power take-off and clutch.
The VA was an air-cooled variant of the 8/1, no compression change-over and a market in the far eastern countries where water cooling was a problem. It never reached high sales figures and was replaced by the later series of air-cooled engines such as the HA, HB etc. It is not particularly popular with preservationists and has achieved a small rarity value.
The JP series ran from 1926 until the 1960's, and was the original Lister Cold-Starting diesel engine. It had a few quirky design details such as the bevel gear drive to the injection pump, but it was a good engine at a time when it was appreciated by agricultural and industrial users. Many went into marine applications such as canal boats and barges, and during WW2 a huge volume of searchlight generating sets was produced by Listers with Mawdsley electrical gear.